Charge controller for multiple sources

[cha0s]

Can anyone recommend a charge controller that will handle alternator, solar, and generator/battery charger sources all together. Or at tleast the alternator and solar together.

I have a 1.2kw solar installation and 120amp alternator and would like to be able to charge with both at the same time if its possible.

I have an outback fm80 charge controller on the solar and a balmar mc612 on the alternator.
I assume that they can't just be connected to the battery without passing them through a charge controller to make them play nicely with each other.

[Stu Jackson]

Originally Posted by cha0s

>>>>>>>>>>>
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I assume that they can't just be connected to the battery without passing them through a charge controller to make them play nicely with each other.

Incorrect assumption. You do need to set the voltages just a tad different from each other. Maine Sail has written this up many times, as have others. Sorry I don't have it at my fingertips right now.

[newhaul]

The solar and the alternator already have charge controllers and yes they will play just fine as is no issue that I can see happening

[ErikFinn]

Originally Posted by Stu Jackson

Incorrect assumption. You do need to set the voltages just a tad different from each other. Maine Sail has written this up many times, as have others. Sorry I don't have it at my fingertips right now.

Hi Stu,
if you remember where MS wrote about this please let me know, I would also be interested in his gospel. I do remember reading about this but cant remember details. I reckon charging sources to a bus but gospel details would be nice..

[belizesailor]

Mutiple charge sources with multiple controllers is not a problem. The (properly configured) controllers will sort it out.

If you just set them up as normal for battery type etc it will work. Offsetting the voltages a bit may help avoid some back and forth between the controllers.

The idea of a single controller for all charge sources is appealling (I think Ample Power/Next Step has a product like that), but it also means a single point of failure can take out all your charge sources.

[Stu Jackson]

Originally Posted by ErikFinn

Hi Stu,
if you remember where MS wrote about this please let me know,>>>>>>>>>>>>>>

I'd go to his 'sire and the new one under construction:

Support MAINE SAIL

[Pigpen Pete]

Twenty five years ago with our 12 volt system on a 42 ft cruising yacht, I installed an Aerogen wind generator which came with a dump regulator. The regulator briefly dumps 10 amps into a small heater whenever the terminal voltage rises above 14.8, although we adjusted this threshold down for a period when we had gel batteries, and have occasionally added some more amps to the dump.
Despite having a huge variety of other inputs , extra solar panels, manually regulated engine alternator, portable petrol generator, larger wind generators, large towline generator etc, we never needed any other form of regulation and it still works fine.
Mind you its a bit hands on - i.e. we have some big red lights in parallel to the dump, so we know instantly when its dumping and will move to reduce the input or reduce the terminal voltage if it seems excessive.
The system still works well and I've never felt the need for other fancier forms of regulation.
Battery balancing and diodes to block discharge back through the panels etc are still necessary of course but generally the system is easy to run.

[cha0s]

Thanks. I have done a quick scan of main sail's posts but couldn't find the one answering this.
I have emailed him also.

I have 2 engines, each with a dedicated 120a alternator connected to the 1200ah battery bank (agms) and 1200watts of solar and an inverter charger I think it is 120amps.

I have only been able to get about 30a per hour from the 240v 120a charger into the house bank - plus about 25a max from the solar.
the alternators are sending about 2 amps into them.

I have just had everything connected to a bus bar and then to batteries but feel like I should be getting a lot more amps out of the gear that I have.
I just bought 2x mc614's and a centre fielder for the alternators. Have just had the alternators serviced. Haven't hooked it all up again yet.

If the solar controller is sending 13.6v to the bus bar (that's what the output reading on it says) I don't 'understand why the alternators wouldn't pick that up and assume that the batteries are nearly full. Similarly if the alternator (or 240v charger) is sending in 14.4 v wouldn't the solar charger think that the battery is full?
If I can just connect everything to the battery and it will be fine why would I need a centre fielder? Ie I understand the centre fielder makes the 2 alternators not fight with each other. Why would they fight with each other but play nicely with the shore power and solar.
'People' tell me that agm's can only accept a certain amount of charge and that's why the shore power charger is only sending 30 amps down the line. If that's the case why would there be such a thing as a 120a charger.
I would employ a pro if there was one near me. But there isn't. There are lots of experts - all saying different things.
Realise this may have been covered but I can't find the answer.

[Pigpen Pete]

I'm sure there are greater experts than me but I'll offer the following thoughts...
1. Not a great idea to try to run all of these inputs at once. The input from the solar panels is probably a continuous dc voltage but anything from an alternator or generator or transformed from an original ac energy source is going to be pulsed at various frequencies and therefore they will interfere with one another. They can be run together ( sort of) but there will be losses.
2. The open circuit voltage of your supply affects the rate of charge for any given voltage at the terminals. For instance,the solar panels may OC at 20 volts. If your battery is at 14 volts then the voltage difference driving the current flow is 6 volts only, maybe less if you have some diodes in the line. With the inbuilt regulators in other charging systems they may almost stop charging when the battery terminals get above 13.8. ( this is why I cut out much of the regulation in my system and used a manual system of switching in resistances in the alternator feed circuit as required.. to enable fast charging to fill the batts quickly)
3. Having lots of solar and wind input is good as these essentially trickle charge over a long period of time and enable you to minimise reliance on burning fuel to charge.
....
The above is probably oversimplistic and you are obviously running a much bigger system but hope it helps.

[Jetx]

Originally Posted by cha0s

If the solar controller is sending 13.6v to the bus bar (that's what the output reading on it says) I don't 'understand why the alternators wouldn't pick that up and assume that the batteries are nearly full. Similarly if the alternator (or 240v charger) is sending in 14.4 v wouldn't the solar charger think that the battery is full?

I'm no expert, but I think this is where you're getting tripped up. If solar controller and alternators are both connected to your batteries, or bus bar, they cannot ever be "sending" different voltages. Rather, they both "see" the battery voltage, and then respond to that. Both outputs will always be at the same voltage -- the battery voltage (neglecting possible small losses due to resistance in the charging lead, which is only an issue if the controllers don't have a separate sense lead).

As the batteries accept a charge from solar and alternators simultaneously, battery voltage will gradually climb, and the solar controller and alternator regulator will begin to reduce charging current when the battery voltage reaches their defined setpoints for absorption. Later, both the controller and regulator will further reduce output current to just enough to maintain the batteries at their defined float voltage.

The key is that both the controller and the regulators are modulating their current in order to reach/maintain target voltages. But they'll both be "seeing" the same voltage at any given time.

[newhaul]

Originally Posted by cha0s

Thanks. I have done a quick scan of main sail's posts but couldn't find the one answering this.
I have emailed him also.

I have 2 engines, each with a dedicated 120a alternator connected to the 1200ah battery bank (agms) and 1200watts of solar and an inverter charger I think it is 120amps.

I have only been able to get about 30a per hour from the 240v 120a charger into the house bank - plus about 25a max from the solar.
the alternators are sending about 2 amps into them.

I have just had everything connected to a bus bar and then to batteries but feel like I should be getting a lot more amps out of the gear that I have.
I just bought 2x mc614's and a centre fielder for the alternators. Have just had the alternators serviced. Haven't hooked it all up again yet.

If the solar controller is sending 13.6v to the bus bar (that's what the output reading on it says) I don't 'understand why the alternators wouldn't pick that up and assume that the batteries are nearly full. Similarly if the alternator (or 240v charger) is sending in 14.4 v wouldn't the solar charger think that the battery is full?
If I can just connect everything to the battery and it will be fine why would I need a centre fielder? Ie I understand the centre fielder makes the 2 alternators not fight with each other. Why would they fight with each other but play nicely with the shore power and solar.
'People' tell me that agm's can only accept a certain amount of charge and that's why the shore power charger is only sending 30 amps down the line. If that's the case why would there be such a thing as a 120a charger.
I would employ a pro if there was one near me. But there isn't. There are lots of experts - all saying different things.
Realise this may have been covered but I can't find the answer.

ok if you are running all of those at the same time you are putting out about 60 amps. What is the soc of the batteries? What is your average house load?
Imo set your solar controller .2 amp below the charge voltage of the alternator that should make them play better with each other when the mains are running.
Lastly if you are running your shore power charger then your mains should be shut down is: not running . ( you haven't stated if you are running a generator)

[Stu Jackson]

Originally Posted by ErikFinn

Hi Stu,
if you remember where MS wrote about this please let me know, I would also be interested in his gospel. I do remember reading about this but cant remember details. I reckon charging sources to a bus but gospel details would be nice..

Erik,

Coincidentally, he just posted it:

Set your alternator regulators float and absorption voltages higher than the solar controllers absorption & float or add a switch to temporarily disconnect the PV with motor running or purposely set the PV voltage lower than the alt or punch up some DC loads....

If the combination of PV and alt that will allow, if set up incorrectly, the PV voltage to creep beyond alt reg set point. When this occurs the regulators only choice is to kill the alternator field until voltage drops back to within the regulators limiting point.. Killing the alt field shuts off the stator pulse and thus no tach.

if you can live without the tach it is really no big deal...

From this link: Engine Tach issue

Good luck.

[belizesailor]

Once the batteries are fully charged (per external regulator), you are likely to get the no tach output issue with many external alternator regulators, regardless of how you set up the various controllers.

As suggested, adding a load at that point should drop the battery voltage a bit and cause the external regulator to kick back in.

[Sailmonkey]

Originally Posted by cha0s

'People' tell me that agm's can only accept a certain amount of charge and that's why the shore power charger is only sending 30 amps down the line. If that's the case why would there be such a thing as a 120a charger.

.

What is your state of charge when you think you should be getting more current into the batteries?

If they’re almost full, they’re still lead acid and will still have their acceptance rate drop off.

[belizesailor]

Originally Posted by cha0s

...
'People' tell me that agm's can only accept a certain amount of charge and that's why the shore power charger is only sending 30 amps down the line. If that's the case why would there be such a thing as a 120a charger.
...

Acceptance Rate (how many amps you can push into a battery bank) is primarily based on battery chemistry, state of charge (SOC), and battery bank capacity.

If SOC is high, then acceptance rate will be relatively low. So, typically, a high output charger will only output lots of amps when then SOC is relativley low. A high output charger is handy for bringing a big bank's SOC up quickly, but will taper off as SOC increases. You could use a smaller charger, but total charge time will be substantially longer. If the application is a large bank hooked up to shore power for a long time (like weekend use followed by the boat being on shore power all week or more) then thats not a problem. If you want to bring the bank back up relatively quickly then you need to be able to push big amps.

By contrast, if you want to bring a big bank up quickly with a genset as the power source, to limit genset run time, then you need a big charger...and a big genset.

Ive got some AGMs installed ashore (off grid house) which the manufacturer states have an "unlimited" acceptance rate. I cant wait to test that statement when they are nearing the end of their useful life...Im thinking a lightening rod directly connected to the bank...and a well shielded camera to record the fun from a safe distance. 😎